The California Fish and Wildlife Department is evacuating all fish from two of its hatcheries outside of Sacramento to avoid "catastrophic fish losses" that could arise due to increasing water temperatures this summer.
Rainbow trout from the American River Hatchery, as well as salmon and steelhead from the Nimbus Hatchery, are expected to be moved out to lakes around the state by the end of this week. This is the first time the entire stocks of both hatcheries have had to be evacuated, according to a statement from the department.
The department estimates that water temperatures in the hatcheries will exceed 78 degrees this summer, making it too hot for the young fish to survive to maturity. While there are measures in place that could help lower water temperatures under normal circumstances, California’s massive drought has dried up their chances of working.
Normally in the face of high water temperatures, the hatcheries could pull cold water from the depths of the nearby Folsom Lake. This year though, the drought has rendered the lake too warm to draft water from.
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While the fish are planned to be released in their normal locations, the timeframe for release has had to be pushed six months ahead of the normal schedule of February. This means the released fish could have more trouble surviving out in the wild.
"We will track all changes involved in the evacuation and evaluate how fish react to being released early," said Dr. William Cox, CDFW State Hatchery Program Manager, in the statement. "Ultimately we could develop new release strategies based on what we learn."
According to the statement, the remaining 20 state-managed hatcheries are expected to make it through the summer months and into the winter season without having to evacuate fish.